Method and apparatus to crimp a sheet

Abstract

A method is provided to crimp a sheet having, before crimping, a thickness, a moisture, a composition, and a width, the method including: obtaining one pre-crimping sheet characteristic among the thickness of the sheet, the moisture of the sheet, the composition of the sheet, and the width of the sheet; crimping the sheet to form a plurality of corrugations on the sheet, the crimping including providing a pair of crimping rollers defining a nip therebetween, the nip having a nip size, and inserting the sheet in the nip; evaluating a post-crimping characteristic of the sheet after crimping; and varying the nip size on the basis of the obtained one of the pre-crimping sheet characteristic, and on the basis of the evaluated post-crimping sheet characteristic. An apparatus to crimp a sheet is also provided.

1 .- 15 . (canceled) 
     
     
         16 . A method to crimp a sheet having, before crimping, a thickness, a moisture, a composition, and a width, the method comprising:
 obtaining one pre-crimping sheet characteristic among the thickness of the sheet, the moisture of the sheet, the composition of the sheet, and the width of the sheet;   crimping the sheet to form a plurality of corrugations on the sheet, the crimping including:
 providing a pair of crimping rollers defining a nip therebetween, the nip having a nip size, and 
 inserting the sheet in the nip; 
   evaluating a post-crimping characteristic of the sheet after crimping; and   varying the nip size on the basis of the obtained one of the pre-crimping sheet characteristic, and on the basis of the evaluated post-crimping sheet characteristic.   
     
     
         17 . The method according to  claim 16 , wherein the sheet is a sheet of a material containing alkaloids or a plastic sheet. 
     
     
         18 . The method according to  claim 16 ,
 wherein the sheet has, before crimping, a mechanical characteristic, a stickiness, and a temperature, and   the method further includes:
 determining one additional pre-crimping sheet characteristic among the mechanical characteristic of the sheet, the stickiness of the sheet, and the temperature of the sheet, and 
 varying the nip size on the basis of the determined one of the additional sheet pre-crimping characteristics. 
   
     
     
         19 . The method according to  claim 16 , wherein the evaluating a post-crimping characteristic of the sheet after crimping includes evaluating a characteristic of the plurality of corrugations formed on the sheet after crimping. 
     
     
         20 . The method according to  claim 19 ,
 wherein the plurality of corrugations have a pitch and an amplitude, and   wherein evaluating a characteristic of the plurality of corrugations includes evaluating the pitch or the amplitude of at least one corrugation of the plurality.   
     
     
         21 . The method according to  claim 20 , wherein the evaluating the pitch or the amplitude of at least one corrugation of the plurality further includes determining a profile of at least one corrugation. 
     
     
         22 . The method according to  claim 16 , further comprising removing at least a portion of the sheet on the basis of the evaluated post-crimping characteristic of the sheet. 
     
     
         23 . The method according to  claim 16 , further comprising:
 setting a first nip size on the basis of the obtained one of the pre-crimping sheet characteristics; and   adjusting the first nip size to set a second nip size on the basis of the evaluated post-crimping sheet characteristic of the sheet.   
     
     
         24 . An apparatus to crimp a sheet having, before crimping, a pre-crimping characteristic among: a thickness, a moisture, a composition, and a width, the apparatus comprising:
 a transport device configured to transport the sheet along a transport direction;   a pair of crimping rollers to crimp the sheet forming a plurality of corrugations on the sheet, the pair of crimping rollers defining a nip therebetween, said nip having a nip size;   a sensor configured to evaluate a post-crimping characteristic of the sheet, the sensor being located downstream of the pair of crimping rollers in the transport direction;   one of the following:
 a sensor configured to evaluate one of the pre-crimping characteristics of the sheet, and to send a signal function of the evaluated one of the pre-crimping characteristic, the sensor being located upstream the pair of crimping rollers in the transport direction, and 
 a memory containing data relative to one of the pre-crimping characteristics of the sheet; 
   a controller configured to receive the signal function of the evaluated one of the pre-crimping characteristics or to retrieve the data relative to one of pre-crimping characteristics;   a first actuator configured to vary the nip size; and   a feedback control loop system configured to activate the first actuator on the basis of the evaluated one of the pre-crimping characteristic of the sheet or on the basis of the data retrieved relative to one of the pre-crimping characteristics, and on the basis of the evaluated post-crimping characteristic of the sheet.   
     
     
         25 . The apparatus according to  claim 24 , wherein the sensor configured to evaluate one of the pre-crimping characteristics of the sheet includes a sensor configured to measure the thickness of the sheet, the sensor configured to measure the thickness of the sheet including one of:
 a mechanical sensor including a wheel or a skate in contact to the sheet,   an optical sensor to impinge an electromagnetic beam onto the sheet, and   an interferometer.   
     
     
         26 . The apparatus according to  claim 24 , wherein the sensor configured to evaluate one of the post-crimping characteristics of the sheet includes a sensor configured to evaluate a characteristic of the plurality of corrugations. 
     
     
         27 . The apparatus according to  claim 26 , wherein the sensor configured to evaluate a characteristic of the plurality of corrugations includes a laser profiler. 
     
     
         28 . The apparatus according to  claim 27 , wherein the controller is connected to the laser profiler, the controller being further configured to determine an amplitude or a pitch of the profiles obtained by the laser profiler. 
     
     
         29 . The apparatus according to  claim 24 , further including one of:
 an ambient temperature sensor configured to measure an ambient temperature of an environment where the sheet is located and to emit a signal representative of the measured ambient temperature;   an ambient humidity sensor configured to measure an ambient relative humidity of the environment where the sheet is located and to emit a signal representative of the measured ambient relative humidity;   a stickiness sensor configured to measure a stickiness of the sheet at a given location and to emit a signal representative of the measured stickiness; and   a transparency sensor configured to measure a transparency of the sheet and to emit a signal representative of the measured transparency, the transparency sensor being located downstream of the pair of crimping rollers.   
     
     
         30 . The apparatus according to  claim 24 , further including a second actuator configured to discard at least a portion of the sheet, the feedback control loop system being further configured to activate the second actuator on the basis of the evaluated pre-crimping characteristic of the sheet or on the basis of the data retrieved relative to one of the pre-crimping characteristics or on the basis of the evaluated post-crimping characteristic.